Several new methods are proposed for the synthesis of polynuclear aromatic hydrocarbons. These routes involve cycloaddition reactions of arynes with triazoles, isoindoles, pyrroles and their oxygen analogs to give, after loss of the bridging group, the polycyclic aromatic hydrocarbon. The syntheses are particularly designed to prepare (1) linearly annealated benzenes such as tetracene, pentacene and the unknown octacene, (2) selected carcinogenic polynuclear aromatic hydrocarbons such as benzanthracene and dibenzanthracene and their polyfluoro derivatives for which to study the K-region epoxidation theory of carcinogenesis, and (3) anthracenes of novel substitution. BIBLIOGRAPHIC REFERENCES: "Reactions of Sodium Borohydride in Acidic Media. II. Selective Reduction of Aldehydes with Sodium Triacetoxyborohydride," Chem. Commun., 535 (1975), G.W. Gribble and D.C. Ferguson. "Reactions of Sodium Borohydride in Acidic Media. III. Reduction and Alkylation of Quinoline and Isoquinoline with Carboxylic Acids," Synthesis, 650 (1975), G.W. Gribble and P.W. Heald.